It is generally well known that conduits or pipes which are employed for conducting fluids, for example, sanitary sewer pipes, storm sewer pipes, water lines and gas lines, frequently require repair due to leakage. The leakage may be inwardly, from the environment into the pipe, or outwardly, from the pipe into the environment. Leakage of this type may be due to improper initial installation of the pipe, deterioration of the pipe itself due to aging or the effects of corrosive materials, cracking of the pipe or pipe joints due to environmental conditions such as earthquakes or similar natural or man-made vibrations, or any other such causes. Regardless of the cause, such leakage is undesirable, at best, and may result in waste of the fluid being carried by the pipe, damage to the environment and the possible creation of public health hazards.
Because of ever increasing labor and machinery costs, it is becoming increasingly more difficult, at least economically, to dig up and replace those pipes or portions of pipes which may be leaking. As a result, various methods have been devised for the in situ repair or rehabilitation of the existing pipes, thereby avoiding the expenses and hazards involved in digging up and replacing the pipes. One of the most successful of such repair or rehabilitation processes which has been developed is called the Insituform process, which is described in U.S. Pat. Nos. 4,009,063; 4,064,211; and 4,135,958, the contents of which are hereby incorporated by reference.
Briefly, in the Insituform process, an elongated flexible tubular liner comprised of a felt or similar material which is impregnated with a thermosetting synthetic resin is installed within the existing pipe utilizing an inverting process as described in the aforesaid patents. Before the liner is positioned within the existing pipe, it is standard procedure to make a final television inspection of the conduit prior to the installation of the flexible tubular liner. During this television inspection, a video tape record, usually with voice comments, is made of the existing conduit which lists each service connection or service pipe outlet, noting the size of the opening and the position of the opening and the distance of the opening from the center point of a downstream manhole.
Once the liner is in place within the pipe, the liner is pressurized from within, preferably utilizing a high temperature fluid, to force the liner radially outwardly to engage and conform to the interior surface of the pipe. While the pressure is maintained, the resin is cured to form a relatively hard, tight-fitting, rigid pipe lining which effectively seals any cracks, and repairs any pipe or joint deterioration to prevent further leakage either into or out of the pipe.
When such a liner is installed in a pipe, such as a sanitary sewer main, which includes a plurality of connecting service entrances or service pipe outlets, such as smaller laterals which carry sewage from individual sources into the main pipe, all of the service pipe outlets or laterals are effectively covered over and sealed by the liner. It, therefore, becomes necessary to either gain access to the service pipe outlets, in order to cut holes through the liner, or to provide a remotely controlled means to locate and cut out the portion of the liner that covers over the service pipe outlet or lateral entrances.
Prior art cutters which have been previously employed for this purpose are described in the U.S. Pat. Nos. 4,197,908 and 4,819,721, which are hereby incorporated by reference. Generally, after the flexible liner is installed, a television camera is installed in the new flexible liner in conjunction with a remotely controlled cutting device. The camera and cutting device are activated to survey or scan the interior surface of the main pipe to provide a visual display for the operator. The camera and cutting device are slowly pulled forward along the main pipe by a cable. The video camera scans the interior of the main pipe until the presence of a service pipe outlet or lateral is detected. The presence of a service pipe outlet can normally be detected by the camera since a depression or dimple generally forms over the service pipe outlet opening due to the pressures imposed upon the liner during curing and the lack of support over the service pipe outlet opening. Thus, the presence of a generally circular dimple or indentation having a diameter which approximates that of a sewage service pipe outlet within the liner indicates the presence of a connecting service pipe outlet which must be opened to permit the free flow of sewage into the sewer pipe.
However, on occasion it is difficult to locate the service pipe outlets because the dimple or indentation is not always readily locatable or identifiable and, accordingly, much time and effort is devoted to this operation significantly increasing the cost of installing the liner.
The present invention overcomes many of the disadvantages inherent in the above-described method for locating the service pipe outlets by providing a remotely controlled locator material dispensing apparatus which dispenses locator material onto an interior area of the main pipe before it is lined. After a flexible tubular liner is installed within the main pipe, a sensor is provided for readily sensing the location of the locator material and, hence, the service pipe outlets. Consequently, the method and apparatus of the present invention allows the service pipe outlets to be easily, readily and positively located. The present invention further provides an alternate method for locating service pipe outlets where the service pipe includes a cleanout (access device). In this alternate method, the flexible liner is first installed in the main line and using the cleanout, locator material is applied to the back side of the flexible liner that spans each service pipe outlet. Thus, use of the present invention results in considerable savings in time and expense for the installation of flexible tubular liners within conduits.